Furnace.



Patented Sept. I6, .I9ID2.'

42 Sheets-Shelpt I.

@Qorneys UNITED STATES PATENT EEICE. y

`DOALD SKINNER MCDONALD, OF MABOU, CANADA.

FURNACE.

SPECIFICATION forming part of Letters Patent No. 709,107, dated September 16, 1902.

Application filed January 10. 1902. Serial No. 89,109. (No model.)

To all whom t may con/cern:

Be it known that I, DONALD SKINNER Mc- DONALD, a subject of the King of Great Britain, residing at Glendyer, Mabou, county of Inverness, Cape Breton, Province of Nova Scotia, Canada,AV have invented certain new and useful Improvements in Furnaces; and I do hereby declare that the following is a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it 'appertains to make and use the same.

My invention relates to improvements in furnaces of that class known to the art as hotair furnaces; and the object inview is the provision of a simple and compact construction arranged to receive pure cold air from the outside of a house to heat the same to the required temperature and provide for equable distribution to a series of conveying-fines, as well as to insure the circulation of smoke and other products of combustion in a manner to heat the series of chambers. Provision is also made for controlling the circulation of air and of the products of combustion to suit the demands of the service.

Further objects and advantages of the invention will appear in the course of the subjoined description, and the novelty in the construction and arrangement of parts will be defined by the claims.

In the drawings hereto annexed, forming a part of this specitication, Figure 1 is a vertical central sectional elevation through a hotl means of the feet 9.

air furnace embodying my invention. Fig. 2 is a vertical section at right angles to Fig. 1 and in the plane indicated by the irregular line 2 2 on Fig. 1. Fig. 3 is a sectional plan view taken in the plane of the dotted line 3 3 on Fig. 1.

The same numerals of reference denote like parts in each iigureof the drawings.

5 designates the front of the furnace, 6 is the rear, and 7 8 are the sides. These parts may be constructed of metal in any suitable style and dimensions, andthe casing thus provided is supported at a proper elevation by The top 10 of the casing is provided with a smoke-outlet 11.

12, 13, and 14 designate a series of boxes forming a series of chambers within the casing, and the lowermost box 12 is arranged directly above the grate 1 5, so as to form there'- With an intermediate combustion-chamber 16. Access` to this combustion-chamber is obtained through the fuel-door 17, and the ashes are adapted to fall into the pan or tray 1S. The lowermost box 12 extends the full length of the casing, so that it will abut againstthe front and rear walls 5 and 6, respectively; .but this box 12 is not equal in width to the surrounding casing, because the sides of the box lie Within and parallel to the sides 7 8 of the casing, (see Figs. 2 and 3,) thereby forming the updraft side Iiues 19 19a. The cold air is supplied to the chamber of the lower box 12 through an inlet-opening20, Which is provided in the rear wall 6 in 4the plane of the chamber of said hot-air box 12. Lateral outlet-openings 21 22 are provided at the sides of the hot-air box 12 and at the opposite end thereof from the air-inlet 20, said exitopenings 21 22 extending throughthe sides 7 S of the casing. (See Fig. 3.) The second hotair box 13 is disposed above the box 12, so as to leave an intermediate circulation-space 23 for the heat and products of combust-ion, and this box 13 extends the full length and Width of the external casing. To provide for the passage therethrough of the heat and products of combustion, this intermediate hot-air box 13 is provided with thesmoke-tube 24,

the latter being arranged in a vertical position near one end of the box 13 and substantially in the vertical plane of the smoke-outlet 11. The cold air is supplied to the box 13 through an inlet-opening 25, which is provided in the rear wall 6, and the warm air is permitted to escape from this intermediate box by an opening 26, which is provided in the front 5 of the inclosing casing.

The top hot-air box 14 is arranged above the box 13, so as to form an intermediate flue 2S, and it lies below the top 10 of the casing in a position to form the uppermost flue 29. |Ihis top box is equal to the full'width of the casing, but it extends from the rear wall to a point near the front wall, thereby producing an updraft connecting flue 30 beyond the front end of the box, said flue 30 serving to establish communication between the tlues 28 29. The hot-air box 14 is furthermore provided near its rear end with a vertical smoketube 3l, which is disposed in the plane of thc IOO smoke-tube 24, and with the smoke-outlet 1l; but the passage of the smoke through this tube-31 is adapted to be checked by closing the damper 32, the latter being controlled by the damper-rod 33, whereby the escaping products of combustion from the tube 24 may be caused to pass through the flue28 up the line 30 and then back through the Hue 29 and finally through the smoke-outlet 11. The cold air is admitted to the top box 14 through an inlet-opening 34, which is provided in the rear wall and the air is permitted to escape from this top box by means of an outlet-pipe 35, the latterl extending through the top 10 of the furnace.

36 designates a cold-air conduit which is attached to the back wall 6 of the casing ina position to nclose the inlet-openings 20, 25, and 34 to the hot-air boxes 12, 13, and 14, respectively. The upper end of this cold-air conduit is closed by a head 37; but the lower end of said conduit is'open, so that cold air may readily flow thereinto. y In thiscouduit and below the opening 2O of the lowermost box 12 is arranged a damper 38, which is adapted to be manipulated by the rod 39.

The front 5 of the inclosing casing is preferably equipped with the cleaning-doors 40 41, by which access may be obtained to the iiues 23, 28, and 29 for the purpose of removingthe soot and ashes which may accumulate within the furnace.

If desired, the lowermost hot-air box 12 may be provided with a central smoke flue or passage 42, the same extending longitudinally of the furnace, as clearly shown by Figs. 2

and 3, whereby the smoke and products of.

combustion may pass centrallythrough the flue 42 and on both sides of the box l2 through the iiues 19 19a, thereby increasing the heating area of the lowermost box, which is exposed directly to the heat from the bed of incandescent fuel in the combustion-chamber 16.

By reference to Fig. l it will be seen that the feathered arrowsindicate the course of circulation of theheated products of combustion from the chalnber 16 to the outlet 11, while the unfeathered arrows show the course of circulation of the cold air, which is heated in the boxes 12, 13, and 14 and is discharged by the warm-air outlets thereof. The damper 32 may be opened when it is desired to establish a direct draft from the chamber 16 tothe smoke-outlet-as, for example, when starting a lire in the furnace. The closing of this damper 32 is also advantageous in the event of cutting olf some of the hot air from the furnace. This object may also be accomplished by adjusting the damper 3S in the cold-air liue 36, thereby regulating the volume of air through the line and the supply to the series of hotair boxes 12, 13, and 14.

Changes within the scope of the appended claims may be made in the form and proportion of some of the parts while their essential features are retained and the spirit of the invention is embodied. Hence I do not de-A sire to be limited to the precise form of all the parts as shown, reserving the right to vary therefrom.

1. A hot-air furnace comprising a suitable casing, a lower hot-air box having side and central smoke-fines traversing it and having a cold-air inlet and a hot-air outlet, an upper hot-air box having a smoke-tube and a hotair outlet as well as a cold-air inlet, an intermediate hot-air box having a-smoke-tube and air inlet and outlet, and a damper arranged in operative relation to the smoke-tube of the upper box, substantially as described.

2. A hot-air furnace comprising a rectangular casing, a series of hot-air boxes having horizontal flat top and bottom sides traversing the casing, each box having a cold-air inlet at one end and a hot-air outlet at the other, a'fire-chainber located at the bottom of the casing, Hue-chambers located between the boxes and above the uppermost one thereof, smoke passages connecting the successive flue-chambers at opposite sides of the casing whereby to cause an alternating circulation of the flue-gases back and forth, a flue connection connecting the last one of said iiuechambers only with the chimney, and an alternative passage-way for the flue-gases having a damper therein and located immediately beneath said flue connection connecting the last two flue-chambers, whereby to regulate the circulation of the flue-gases.

3. A hot-air furnace comprising a rectangular casing, a series of hot-air boxes having horizontal top and bottom sides traversing the casing, each box having a cold-air inlet at one end and a hot-air outlet at the other, a fire-chamber located at the bottom of the casing, flue -chambers located between the boxes and above the uppermost one thereof, smokepassages connecting the successive Hue-chambers at opposite sides of the casing whereby to cause an alternating circulation of the flue-gases back and forth, a fine connection connecting the last one of said linechambers only with the chimney, analternative passage-wayfor the fine-gases having a damper therein and located immediately beneath said liue connection connecting the last two flue-chambers, whereby to regulate the circulation of the flue-gases, and doors formed opposite each of said fine-chambers.

4. A hot-air furnace comprising a rectangular casing, a series of hot-air boxes having horizontal top and bottom sides traversing the casing, each box having a cold-air inlet at one end and a hot-air outlet at the other, a fire-chamber located at the bottom of the casing, flue-chambers located between the boxes and-above the uppermost one thereof, smoke passages connecting the successive flue-chambers at opposite sides of the casing whereby to cause an alternating circulation of the fine-gases back and forth, a flue connection connecting the last one of said finelocv chambers `only Withthe chimney, an alterna-y tive passage-Way for the nue-gases having a damper therein and located immediately beneath said flue connection connecting the last two Hue-chambers, whereby to regulate the circulation of the due-gases, doorsformed opposite each ofsaidiiue-chambers, anda coldair-inlet box comprising a passage-way formed on the exterior rear Wall of the casing and connectiug the inlet openings of said hot-air :o

boxes, substantially as'described In Witness whereof I have hereunto set my hand in the presence of two Witnesses.

DON ALU SKINNER MCDONLD.

Witnesses:

WALTER GILLIS, DONALD SMITH. 

